Catalytic cracking
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I’m new to catalytic cracking, and I have a small question for everyone: why is it necessary to maintain the slurry circulation as long as the reaction-recovery system continues to operate in a catalytic cycle? If the slurry circulation is interrupted for an extended period, single-regenerator fluidization should be adopted. I really can’t figure it out
With the catalyst circulating between the two vessels, some catalyst will inevitably enter the distillation tower; therefore, the slurry circulation is primarily used to flush the catalyst at the bottom of the distillation tower
If, after a long interruption in the slurry circulation, reaction gases still carry catalyst into the distillation column, this will cause the catalyst particles to rise to the level of the floating valve trays, thereby blocking those trays； Entering the re-refining system causes wear on its equipment and pipelines; therefore, when the slurry circulation is interrupted for an extended period, it is necessary to ensure that no catalyst enters the distillation column. To this end, the two vessels are disconnected, allowing the catalyst to flow solely through one vessel.